The present invention relates to instruments for electrical measurement and, in particular, to the minimization of the effects off interfering signals.
Measurement instruments for making electrical measurements, particularly high accuracy and/or low level measurement can be adversely affected by interference from signals generated by the instruments themselves. For example, power supplies, particularly switching power supplies, may generate substantial interference. As a further example, digital logic control circuitry may do the same. The high frequency content of such signals tends to make it difficult to isolate these signals from the measurement section of the instrument.
It is even more of a problem when attempts are made to miniaturize an instrument and/or to more densely arrange instruments. One desirable configuration is to design instruments that can be implemented on cards suitable for use in devices such as personal computers. However, it is difficult to provide power and control of the measurement section while maintaining measurement integrity.